This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In order to answer the question: are currently available screening tests for fat malabsorption adequate to detect steatorrhea, increased fecal fat excretion, >7g of fat per day, quantitatively, in patients with chronic pancreatitis, we propose to do a study comparing the 72 hour quantitative fecal fat excretion measurement to four screening tests. The most commonly used screening tests are: serum carotene, qualitative fecal fat stain, serum trypsin and the secretin stimulation test. It was our observation, from previous studies, that the screening tests led to false positive results in approximately 50% of our subjects compared to the quantitative fecal fat excretion measurement. Patients with chronic pancreatitis may have similar symptoms whether they have mild to moderate or severe disease. The ability to adequately categorize these patients into the two groups is important in both the clinical and research setting. In our ongoing and future studies, it is mandated that we have subjects with severe chronic pancreatitis and steatorrhea therefore, it is imperative that we accurately categorize our subjects. Clinically, it is important to know because enzyme treatment and other interventions achieve different results in patients with severe disease versus mild to moderate disease. We expect this study to definitely define the relative accuracy of these screening tests compared to the quantitative fecal fat excretion measurement, which is the gold standard.